Culture

Tender perennial that is winter hardy to USDA Zones 9-11. In St. Louis, it is grown as an annual. It is easily grown in moist, organically rich, well-drained soils in full sun. Tolerates very light shade, but flowering decreases as the amount of part shade increases. Also tolerates drought. Purchase plants in spring and set out after the last frost. Plants produce little if any seed and must be vegetatively propagated. Most hybrid cultivars are patented thus prohibiting vegetative propagation. Deadheading is not required. Unlike its petunia relatives, calibrachoa does not typically decline during the heat of St. Louis summers.

Noteworthy Characteristics

Calibrachoa or trailing petunia is a tender perennial which produces flowers that look like small petunias. These are compact, mounded plants which grow 3-9” tall on mostly trailing stems. Sometimes commonly called million bells, these plants are prolific bloomers that produce hundreds of 1” wide flowers from spring to frost. Flower colors include shades of violet, blue, pink, red, magenta, yellow, bronze, and white. Calibrachoa is not recognized as a separate genus by many authorities including the Royal Horticultural Society (RHS) and Hortus Third. It is sometimes sold in commerce as Petunia ‘Million Bells’.

Problems

No serious insect or disease problems.

Garden Uses

Best in hanging baskets, containers or as a small area ground cover. Also may be used in border fronts or rock gardens.